Project Summary/Abstract More than 7 million esophagogastroduodenoscopies (EGDs) are performed in the US annually, largely to screen for pathology in patients with chronic Gastroesophageal Reflux Disease (GERD). The vast majority of these EGDs find no disease nor require clinical intervention. Based on Medicare reimbursement estimates, substantial savings can be achieved by reducing the number of EGDs performed in these patients. In addition to this direct monetary cost-savings, reducing the number of EGDs would yield a reduction in the indirect costs associated with the procedure, such as time lost from work for the patient and persons accompanying the patient, sedation, and recovery. Moreover, the potential patient benefits of the EGDs are currently diminished by the limited diagnostic accuracy resulting from the random nature of esophagus biopsy sampling. We propose to develop and prototype a diagnostic tool, in the form of an ingestible tethered capsule, which would be swallowed (temporarily) by the patient and which would optically map the histologically relevant tissue properties of the esophagus epithelium in real time, based on scanned elastic-scattering spectroscopy (ESS) measurements. These types of pathology maps would be valuable in two clinical settings: one aimed at the primary care physician (PCP), to establish the presence of esophagitis and/or Barrett?s esophagus, the second aimed at the management of those diseases by gastroenterologists. This proposal focuses on the implementation for PCPs, by which the device could serve for preliminary screening to rule out the presence of Barrett?s esophagus (BE) and/or esophagitis in patients with symptoms of GERD. Only about 20% of patients with chronic GERD are found to have BE at time of endoscopy. Thus, our envisioned device could potentially eliminate the need for EGD, which is the current standard of care, in up to 80% of patients with symptomatic reflux. Integrated video imaging capabilities in the tethered capsule will also enable visual inspection of the esophagus, without the cost of endoscopy, and will enable the co-registration and documentation of esophageal ESS findings. As a future extension of the technology, in the hands of a gastroenterologist, the capability of the system to distinguish dysplasia within BE (which requires prompt treatment) can provide added value by helping the GI endoscopist to better target biopsies to areas of dysplasia. This would lead to a reduction in the number of negative biopsies generated in standard random- biopsy protocols, while increasing the probability of finding conditions that require treatment, by dramatically increasing the pre-biopsy probability of detecting dysplastic tissue. Aims 1 and 2a will concentrate on device design and prototype fabrication; Aim 2b will be a small clinical study to assess device design attributes and user experience; and Aim 3 will be a larger clinical study to assess the potential to provide real-time guidance to the PCP for decisions about referral to GI endoscopy.